Differential pressure sensors are used to measure a difference between pressures of fluid environments. These fluid environments may be located nearby one another or at great distance one from another. Differential pressure sensors come in at least two varieties: i) true differential pressure sensors; and ii) pseudo differential pressure sensors. True differential pressure sensors provide fluid communication between each of the environments and to each of two sides of a differential pressure transducer, respectively.
Pseudo differential pressure sensing can be accomplished using two distinct absolute pressure sensors. Each absolute pressure sensor is exposed to one of the fluid environments so as to measure the fluid environment's absolute pressure. By taking the difference of resulting signals indicative of absolute pressures of the two absolute pressure sensors, a signal indicative of a difference between the two absolute pressures can be generated.
Various types of pressure transducers have various advantages and disadvantages. In some circumstances, for example, it may be undesirable to expose both sides of a differential pressure sensor to high pressures. In such cases, a pseudo differential pressure sensor may be preferable to a true differential pressure sensor. In some cases, the two fluid environments may be located at a great distance one from another. In such cases, use of two remote absolute pressure sensors may provide a good solution for measuring a pressure differential.
Pseudo differential pressure sensors may use two half bridges to construct a full Wheatstone bridge. Each half bridge may generate an electrical signal that corresponds to a pressure of one of the two locations or environments. The differential pressure is then represented by a difference between the signals of the two half bridges. If one of the two bridges, however, has a sensor failure, the system is rendered incapable of measurement of differential pressure.